Well, no... we don't see the actual beheading like we do in the ESB cave scene. We see Anakin's face as he does the deed.
And we certainly don't see slavery. All I saw was a boy working in Watto's shop, and he seemed to like it as well. I didn't see any downsides to Tatooine slavery: no whips, sweating, hard labour. I did see Anakin being able to build his own droid, his own podracer, being able to compete with his favourite sport, living in some nice quarters... I didn't see Shmi in chains either. Is this some romantic version of slavery?
I think seeing Dooku's head bounce away is pretty close. Also, the ESB thing was dream sequence.
As to slavery, Anakin did talk about how he'd be blown up if he tried to escape. Anakin may have built his own pod, but Watto didn't know about it (as evidenced by Jinn convinced him it was his pod). Likely Watto didn't know about 3PO either. If he did, he would have claimed both as his property (as he did with the pod Anakin previously destroyed). Watto didnt do anyhting in the race, Anakin was not awarded any money for his participation, it was split between Watto and Jinn. Anakin racing was just a way for Watto to win money. He even betted against him and laughed at him the whole time, presuming he would fail and Watto would win more betting "everything" against the kid.
So no, its not a "romantic" version. Nice living quarters? Chains? Are you kidding? American slavery in the 16th-18th centuries was NOT the typical historical model. I suggest you pick up a book. We know all the ancient Roman influences Lucas uses...maybe ancient Roman slavery would be a good start for you. Because the kid doesnt have whip marks doesn't mean its not slavery.
We see outright domestic violence in the PT. Another example: in the PT we don't really see any lightsaber deaths. There is the arm in the cantina, but (per your logic thats no different than teh Dooku head scene) and Ben's "magic" disappearing act death. In the PT we see Jinn stabbed and Anakin outright hacks the seperatists to bits while they're begging for mercy.
My point was: we don't really see why Anakin's life as a slave was so bad. I'm sure it was, but I have difficulty with MENTIONING something and not showing what it's really like. Exposition by mentioning something in a dialogue is a very poor way to depict someone's dire living conditions.
And I know a little about slavery in the past. And fact is, sometimes slaves weren't all that bad off apart from the fact they weren't free. But again: I don't see Anakin being surpressed in his freedom in doing what he likes. Obviously he's able to hide a lot form his owner: building a droid AND a podracer. Both require a) being able to steal a lot of parts and b) more living space than I have and c) so much free space taht you can even hide it from your owner.
IMHO, I thought the slavery bit was very poorly done and therefore quite unconvincing.